A buckle stalk for a seat belt is generally fixed at its lower end to the floor of the vehicle, maintains the buckle at a predetermined height from the floor, that is, at a position that does not hinder a passenger from getting in and out of the vehicle, and enables the passenger to easily attach and release the seat belt with one hand. A buckle stalk of this kind must not only keep the buckle at a predetermined height but must also have a tensile strength capable of withstanding any impact load applied thereto from the seat belt and have a certain level of flexibility to enable proper fitting of the seat belt to the user and so that the seat belt adapts to the user's movements.
To satisfy the conditions described above, it is known to use for a buckle stalk wire rope or cable as a core and a flexible wire wound helically around the cable core member and to attach the buckle to the upper end of the cable core. However, such a stalk is both expensive and heavy, thereby increasing the cost of production, and it is also difficult to attach the core member to the buckle.
To solve these problems of conventional buckle stalks, buckle stalks have been proposed (e.g., Japanese Utility Model Publication No. 21412/1982) in which pieces of seat belt webbing are placed on both surfaces of a webbing-like reinforcing core member that is self-supporting but flexible. The pieces of webbing extend in the longitudinal direction of the core member coextensively and are folded back at each end. The folded back end portions are superposed and sewed together, and the outer surfaces of the webbing are covered with a cover or sheath. An anchor member and a buckle member are fitted to the respective ends of the stalk.
In the buckle stalks that use belt webbing described above, however, the webbing itself is not self-supporting; consequently, the stalk is made self-supporting by the reinforcing core member and the cover member, so that the number of components constituting the stalk portion and the number of assembly steps increases; hence, production costs increase. Thus, conventional stalks have left problems yet to be solved.
In order to reduce the number of necessary components and the number of assembly steps of the buckle stalk using conventional webbing, the inventor of the present device proposed previously a buckle stalk in which superposed pieces of webbing are sewed together so as to make the webbing itself self-supporting, thus to enable omission of the reinforcing core member. However, such buckle stalks are not entirely free from a problem of fraying at the ends of each sewed, superposed piece of the webbing. Also, the amount of stitching to make the stalk stiff enough to support the weight of the buckle is considerable. In addition, when the webbing is doubled back and sewed in order to reduce the width of the webbing, the number of webbing layers increases by a factor of four to six, so that sewing by machine is difficult. Therefore, there are several production problems yet to be solved.